Towards combinatorial characterization of the smoothness of Hessenberg Schubert varieties

Fuente: arXiv
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Autori principali: Cho, Soojin, Huh, JiSun, Park, Seonjeong
Natura: Preprint
Pubblicazione: 2023
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author Cho, Soojin
Huh, JiSun
Park, Seonjeong
author_facet Cho, Soojin
Huh, JiSun
Park, Seonjeong
contents A \emph{Hessenberg Schubert variety} is an irreducible component of the intersection of a Schubert variety and a Hessenberg variety, defined as the closure of a Schubert cell intersected with the Hessenberg variety. We consider the smoothness of Hessenberg Schubert varieties of regular semisimple Hessenberg varieties of type $A$ in this paper. We consider the smoothness of the intersection of a Schubert variety and a Hessenberg variety to ensure the smoothness of the corresponding Hessenberg Schubert variety. Specifically, we analyze the structure of the GKM graphs of the intersection of a Schubert variety and a Hessenberg variety. Our results show that the regularity of these GKM graphs is completely characterized in terms of pattern avoidance, which is a necessary and sufficient condition for the intersection to be smooth. This shows that our pattern avoidance provides a sufficient condition for the smoothness of a Hessenberg Schubert variety.
format Preprint
id arxiv_https___arxiv_org_abs_2307_13334
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Towards combinatorial characterization of the smoothness of Hessenberg Schubert varieties
Cho, Soojin
Huh, JiSun
Park, Seonjeong
Combinatorics
Algebraic Geometry
05E14, 14M15
A \emph{Hessenberg Schubert variety} is an irreducible component of the intersection of a Schubert variety and a Hessenberg variety, defined as the closure of a Schubert cell intersected with the Hessenberg variety. We consider the smoothness of Hessenberg Schubert varieties of regular semisimple Hessenberg varieties of type $A$ in this paper. We consider the smoothness of the intersection of a Schubert variety and a Hessenberg variety to ensure the smoothness of the corresponding Hessenberg Schubert variety. Specifically, we analyze the structure of the GKM graphs of the intersection of a Schubert variety and a Hessenberg variety. Our results show that the regularity of these GKM graphs is completely characterized in terms of pattern avoidance, which is a necessary and sufficient condition for the intersection to be smooth. This shows that our pattern avoidance provides a sufficient condition for the smoothness of a Hessenberg Schubert variety.
title Towards combinatorial characterization of the smoothness of Hessenberg Schubert varieties
topic Combinatorics
Algebraic Geometry
05E14, 14M15
url https://arxiv.org/abs/2307.13334